Aiming device

ABSTRACT

An aiming device for insertion of a Kirschner-wire to treat a target bone, comprises an aiming block permitting placement of a Kirschner-wire against the target bone and a forceps connected to the aiming block, the forceps being configured to clamp to the target bone.

FIELD OF THE INVENTION

The present invention relates to an aiming device for insertion of oneor more Kirschner-wires, a bone forceps provided with an aiming device,and a method for the application of an aiming device.

DESCRIPTION OF THE PRIOR ART

Minimal invasive operation practice is frequently performed incombination with cannulated screws in case of screw-osteosyntheses, e.g.at the proximal femur or at the pelvis. In this case a Kirschner-wirehas to be correctly inserted in the bone through a puncture incision inthe soft tissue. Only after the Kirschner-wires correct position isconfirmed via intraoperative fluoroscopy the thick cannulated screw isscrewed in over the previously correctly positioned Kirschner-wire.

From U.S. Pat. No. 4,341,206 “Device for producing a hole in a bone”published on 27.7.1982 a device for producing a hole in a bone is known.An aiming device with a plate is placed at a femur, said plate being incontact with the bone. By means of a handle the surgeon can rigidly urgethe plate against the bone and determine the position of the plate. Aguide tube, respectively a guide sleeve arranged at an angle has a borehole wherein a Kirschner-wire may be inserted in a fitting manner. Theposition of the Kirschner-wire is verified by means of X-ray radiation.An adjustment of the entry angle of the Kirschner-wire is not possiblein case of this device.

JP-A-200/000257 “Cup installation angle setter for artificial hip jointreplacement arthroplasty” published on Jun. 28, 1996 discloses a furtherstate of the art, wherein a fixation member for an aiming guide whichcontacts the bone is manually held. At this fixation member a tiltableguide sleeve for a Kirschner-wire is attached. Therewith the position ofthe guide sleeve and the entry angle of the Kirschner-wire relative tothe bone is fixable.

CH-A-692023 “Instrument for percutaneous bone joint screw bonding”published on Jan. 15, 2002 discloses how two Kirschner-wires arepositioned at a fixation device in one plane. At the same fixationdevice a mounting is attached via a ball-joint, whereby this mounting isprovided with a guide sleeve for a further Kirschner-wire.

WO-A-0119265 “Repositioning device for bone fragments” published on Mar.22, 2001 discloses a device for repositioning bone fragments at thepelvis or at tubular bones. The first clamping member abuts the bone.The second clamping member is provided with bore holes parallel to thefirst clamping member, said bore holes being suitable for receiving aKirschner-wire.

DE-U1-20300988 “Drilling tool for bones, particularly for the proximalfemur” published on Mar. 8, 2003 discloses a drilling tool, particularlyfor a proximal femur with a drill bit and a Kirschner-wire. Theobjective of this invention is that the surgeon can detect without X-rayverification if the Kirschner-wire jams during forwarding the drillingtool.

WO-A-98/04203 “Orthopaedic system allowing alignment of bones orfracture reduction” published on Feb. 5, 1998 discloses an instrumentfor alignment of an instrument with regard to a bone structure undervirtual reality conditions. It can be used e.g. to insert aKirschner-wire without trial drilling. This also allows to reduce theradiation exposure for the patient. The system consists of four parts:an aiming device, a calibrating device, a measuring device and aregulator. This permits a representation of the actual alignment statusin two planes in virtual reality after e.g. X-ray images have beenacquired and stored in a computer. The basis for this is that theinstrument to be inserted can be exactly positioned with regard to itstarget if one aligns two planes at the body to be examined. The highmeasuring and computing effort appears disadvantageous in thisembodiment.

JP-A-11/019095 “Positioning utensil for perforation for knee jointligament bridging” published on Jan. 26, 1999 discloses a tube with achannel wherein a Kirschner-wire is guided. Furthermore, a handle isdisclosed which is connected to one end of the tube and a securingdevice at the other end of the tube for fixation at a femur. The frontend of the tube and the securing device for the femur are provided witha surface that prevents sliding.

JP-A-7/299079 “2 Row nail guide device for positioning of end screw holeof nail for mutual fixation” published on Nov. 14, 1995 discloses a tworow nail guide device for positioning of screw holes and a tibia whereadjustable rods are attached to. At one rod an eccentric guide sleevefor a Kirschner-wire is attached.

U.S. 2002/0099309 A1 “Kirschner-wire with a holding device for surgicalprocedures” published on Jul. 25, 2002 discloses a Kirschner-wire with aholding device. An aiming ring placed on an insertion device allows theplacement of a Kirschner-wire using X-ray radiation.

Furthermore, from the state of the art in osteosynthesis forceps withsprings for opening the legs of the forceps and with locking screws andlocking ratchets for fixing the clamping forces are known. Examples forthis can be found e.g. in the internet on the homepages of manufacturersof medical forceps.

In order to determine the correct spatial position of a Kirschner-wirein the body the Kirschner-wire has previously to be representedintraoperatively in at least two non-parallel planes of projection bymeans of fluoroscopy. Practically, the entry point and entry angle ofthe Kirschner-wire in the bone are already corrected under repeatedradiation until the starting point and the direction of the bore holesare correct in both planes of projection.

For this purpose two C-arms can be simultaneously positioned around thepatient. Alternatively, a single C-arm can be used in alternating planesof projection. As a matter of principle using a single C-arm results inthe disadvantage that in case of a correct alignment of the wire in oneplane a simultaneous check in the second plane is not possible. When theposition and direction of the wires must be corrected in the secondplane of projection no supervision is possible about the alignment inthe first plane. The information concerning the position in the firstplane is not automatically transferred into the second plane ofprojection each. Thus, the correct alignment of the Kirschner-wirerequires an iterative procedure including numerous alternations of theplane of projection and repeated insertion of Kirschner-wires inslightly varied position. This can be cumbersome for the patient andtime consuming for the surgeon.

SUMMARY OF THE INVENTION

It is a first object of the invention to provide an aiming device forthe insertion of one or more Kirschner-wires and which is clampable to abone by means of a forceps. Said aiming device comprising an aimingblock for one or more Kirschner-wires, whereby said aiming block can beput against a bone and wherein said aiming block is connected to afixing device, which is configured as a forceps clampable to a bone.

In a preferred embodiment the forceps comprise a securing function,preferably a ratchet fixation for the clamping legs of the forceps.

In another embodiment the forceps comprise handles or levers suitablefor single hand use of the forceps.

In a further embodiment the aiming block is adjustable in a first planeE1 relative to a bone.

In again a further embodiment a guidance which is moveable in a secondplane E2 is attached to the aiming block.

In still another embodiment the guidance for the Kirschner-wire ispivotable in the aiming block about an axis of rotation, whichpreferably cuts a longitudinal axis of the guidance.

In a further embodiment a frictional engagement is provided between theguidance and the aiming block, preferably in the range of the axis ofrotation, so that the guidance is kept at a selected defined anglewithin the aiming block in a self-locking manner.

It is a second object of the invention to provide an aiming device forthe insertion of one or more Kirschner-wires and which is provided witha pivotable guidance for said one or more Kirschner-wires. Said aimingdevice comprising an aiming block for one or more Kirschner-wires,whereby said aiming block can be put against a bone and wherein saidaiming block is connected to a fixing device which is clampable to abone. Furthermore, said guidance is pivotably attached to the aimingblock.

In another embodiment the guidance for the Kirschner-wire is pivotablein the aiming block about an axis of rotation, which preferably cuts alongitudinal axis of the guidance.

In a further embodiment the aiming block is adjustable in a first planeE1 relative to a bone.

In yet a further embodiment the guidance is moveable in a second planeE2.

In still another embodiment a frictional engagement is provided betweenthe guidance and the aiming block, preferably in the range of the axisof rotation, so that the guidance is kept at a selected defined anglewithin the aiming block in a self-locking manner.

In a further embodiment the fixing device is configured as a forcepswith a securing function, preferably a ratchet fixation for the clampinglegs.

In another embodiment the aiming block is adjustable in a third planerelative to a bone and the fixing device.

In yet another embodiment the first and second plane E1, E2 andpreferably the third plane E3 are at an angle between 90° and 160°relative to each other.

In a further embodiment the aiming block is displaceable relative to thefixing device and parallel to the third plane E3.

In still a further embodiment the forceps comprise clamping legs whichare preferably curved or cranked.

In another embodiment the forceps comprise clamping legs which areprovided with rough or structured surfaces at their surfaces abutting abone.

In a further embodiment the aiming block is attached to a rail, which isguided and fixable preferably in the range of the pivoting point of theclamping legs and particularly in a recess.

In still a further embodiment the rail is fixable at the forceps bymeans of a fixation means, preferably a knurled screw.

In another embodiment the aiming block is longitudinally and/ortransversely displaceable and/or rotatable relative to the rail ifnecessary and fixable at the front end of the rail.

In a further embodiment the rail is guided in a rear section parallel tothe forceps in the plane E3, and wherein the front section of the railis configured at an angle W with respect to the rear section, wherebythe angled proximal section is guidable parallel to the external contourof a bone.

In still a further embodiment the angle W is adjustable or fixed and isin a range between 90 and 160°, typically about 150°.

In another embodiment the aiming block and/or the guidance are made of aradiolucent material, preferably PEEK.

It is a third object of the invention to provide a bone forceps with alocking means, e.g. a ratchet fixation and clamping legs for abutment ata bone, whereby the bone forceps is provided with an aiming device forone or more Kirschner-wires.

In a further embodiment the aiming device comprises an aiming block andat least one guidance for at least one Kirschner-wire, said guidancebeing pivotable in the aiming block.

In another embodiment the aiming block is adjustable by means of adisplaceable rail at the bone forceps.

BRIEF DESCRIPTION OF THE APPLICATION OF THE INVENTION

The preferred application is the exact positioning of Kirschner-wires,which are suitable as guiding elements for cannulated screws in therange of the proximal femur or at the pelvis.

At the beginning of the operation the Kirschner-wire is inserted in theaiming block, so that the tip of the wire is visible at the remote endof the bore hole of the guide sleeve.

Subsequently, the direction of the Kirschner-wire and of the aimingblock as well is adjusted in the first plane of projection and checkedby means of radiation perpendicularly to this plane and eventuallycorrected.

As soon as the direction of the Kirschner-wire is adjusted in the firstplane the positioning in the second plane of projection is realisedaccordingly to the desired direction. Again the position of theKirschner-wire should be checked by means of radiation and a navigationdevice and corrected, if necessary.

After being positioned by means of the aiming device the Kirschner-wirecan be inserted in a positional correct manner and without furthersupervision.

In a preferred embodiment of the method for the use of a forceps with anaiming device the forceps are put against a bone so that the rail isapproximately parallel to a bone. Subsequently the rail is displacedrelative to the forceps in the direction of a bone such that the aimingblock abuts the periost.

In another embodiment the aiming block is displaced and/or pivoted atthe front section of the rail relative to the same and fixed.

In a further embodiment the guidance for the Kirschner-wire in theaiming block is tilted about its axis of rotation, respectively alignedby means of X-ray observation.

In yet a further embodiment an X-ray projection is providedperpendicularly to the first and second plane E1, E2 each in order toachieve an optimal alignment.

In another embodiment a navigation device is provided, by means of whichthe spatial position of the Kirschner-wire is determinable anddisplayable before insertion in a bone.

In a further embodiment the navigation device also comprises 2-3 markersM at a bone.

In yet a further embodiment markers M are also attached to the forcepsand/or the Kirschner-wire.

In another embodiment markers M are attached to the forceps and also tothe guidance for the Kirschner-wire.

ADVANTAGES OF THE SOLUTION ACCORDING TO THE INVENTION

Through avoiding repeated drilling due to mistaken positioning of thewire under similar angles a precise placement can be achieved. Afterrepeated drilling with slightly altered angles in osteoporotic bones asin case of conventional procedures the Kirschner-wire disadvantageouslymight run into a an already produced drill channel due to low resistancesuch complicating or preventing a positional correct positioning. Due tothe restriction to two planes of correction only the time of radiationand accordingly the exposure to radiation can be reduced.

A BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates an aiming device fixed at a femur;

FIG. 2 illustrates the possible planes allowing positioning of theaiming device at a femur;

FIG. 3 illustrates a top view on the aiming device;

FIG. 4 illustrates a schematic representation of the aiming device;

FIG. 5 illustrates a top view on a bone with a forceps with aimingblock;

FIG. 6 illustrates a lateral view on a bone with a forceps with aimingblock;

FIG. 7 illustrates an oscillating saw blade for osteotomies;

FIG. 8 illustrates a saw block having a guide plane for an oscillatingsaw blade;

FIG. 9 illustrates a lateral view of a saw block with saw blade.

The aiming device shown in FIG. 1 consists of a radiolucent centralaiming block 10, material e.g. Polyetheretherketone (PEEK) with a highradiolucence, which is displaceably mounted at a forceps 20 (materiale.g. instrument steel). The forceps 20 has clamping legs 25; 26 and isprovided with a ratchet 22, so that the instrument is kept in its actualposition when being clamped to a bone 30. In an exemplary way somemarkers M are shown in FIG. 1. These may be positioned at otherlocations or in another number as well.

The fixation at the bone 30 may be varied, by closing the forceps 20more or less powerfully. Principally, the spatial position of theforceps 20 with respect to the bone 30 is defined in all planes. Bymeans of the knurled screw 6 (material e.g. instrument steel) in therange of the axis 23 of the forceps the aiming block 10 may be pushed ona rail 5 as far as the periosteum 31 and secured in two planes E1;E3(see FIG. 2). The first portion 5 a of the rail 5 lies on or is parallelto the line of intersection of the planes E2/E3, the second portion 5 bof the rail 5 lies in the plane E2. The axis of rotation 12 in theaiming block 10 is defined with regard to its position relative to thebone 30 by means of the displacement of the rail 5.

Before insertion of the Kirschner-wire 1 in the bone 30, its positionand direction in two planes can be checked and adjusted by means of thepath of the rays and a navigation device. The displaceability of theguidance 2 for the Kirschner-wire 1 is preferably self-locking. The rail5 can be fixed by means of the knurled screw 6 in the range of thepivoting point 23 of the forceps. The guidance 2 for the Kirschner-wire1 is pivotable about the axis of rotation 12. The remote end of the borehole 11 of the guidance 2 of the Kirschner-wire 1 abuts the bone 30,whereby the tip of the Kirschner-wire 1 contacts the bone 30, see FIG.3.

FIG. 4 illustrates a schematic view of an aiming device for a fixationby means of bone screws 17. The guidance 2 for the Kirschner-wire 1 ispivotable in the plane E2 in the aiming block 10, the aiming block 10 isattached pivotably in the plane E1 at the end 7 of the rail 5 b. Theaxis of rotation 12 is brought in contact close to the periost 31 of thebone 30.

FIGS. 5 and 6 illustrate schematic diagrams for a forceps 20 with adisplaceably attached aiming block 10, whereby the aiming block 10 isdisplaceably connected with the forceps 20 via the rail sections 5 a, 5b. The guidance 2 is pivotable in the aiming block 10. The aiming block10 is pivotably as well as displaceably attached to the rail section 5b. For the fixation of the aiming block 10 locking screws 16 are used.Embodiments are imaginable which are not provided with a fixation, sincethe aiming block 10 e.g. is not pivotably configured.

A possibility for the application of the aiming device 15 is illustratedin FIGS. 7, 8 and 9. The aiming device 15 permits the matching insertionof Kirschner-wires 1 a, 1 b e.g. in the form that two Kirschner-wiresare driven parallel in the bone 30. On these parallel Kirschner-wires 1a, 1 b a saw block 42 is guided. The oscillating saw blade 41 is putagainst the guide planes 43.

It is advantageous for the function according to the invention that incase of each X-ray projection the path of the rays is perpendicular tothe respective plane E1, E2 of the aiming block.

Only after having the aiming block 10 in a desired alignment theKirschner-wire 1 is inserted in the bone 30. Such only one perforationof the bone 30 is necessary.

The navigation device comprises—as commonly known—also 2-3 markers M atthe bone 30.

Markers M are also attached to the forceps 20, to the Kirschner-wire 1and also to the aiming block 10 and/or to the guidance 2 for theKirschner-wire 1. The navigation device is configured such that itdetects the markers thus allowing a mutual spatial allocation of theparts relative to the bone. By means of this allocation the computer cansubsequently generate a virtual representation of the Kirschner-wire inthe bone, allowing to visualize its final position already before thewire is inserted.

By means of the clamping effect of the forceps 20 the navigation markersM are fixed, and with two markers M at the guidance 2 and/or at theKirschner-wire 1 the direction of the Kirschner-wire 1 is then exactlydeterminable.

The guidance for the Kirschner-wire 1 can also be configured multipart,such comprising guide bores e.g. for two or more Kirschner-wires. Two ormore guidances 2 could be mounted in a parallel manner at the aimingblock 10, so that two or more Kirschner-wires could be inserted in thebone correctly positioned and in a mutual spatial allocationsimultaneously or subsequently via one or more alignments. This can beuseful in case where e.g. the bone has multipart fragments which must beconnected to each other or when the Kirschner-wires are not to be usedfor cannulated screws but as a guidance for other tools, e.g. for sawsfor the osteotomy. In such a case a displaceable guidance as a sawholding guidance might be mounted to the Kirschner-wires, whereon a sawcan be guided in a longitudinally displaceable manner relative to theKirschner-wires. Particularly, the saw holding guidance can beconfigured as a block with two parallel guide bores for Kirschner-wires1. These parallel guide bores would then be approximately congruent withthe two guidances 2 in the aiming block 10.

In an advanced development of the invention the aiming block 10 itselfis used as a saw holding guidance, whereby the guidances 2 mutate to theguide bores of the block. In this embodiment the aiming block 10 isremovable as a whole from the rail 5 b and is subsequently displaceableparallel in the direction of the previously inserted Kirschner-wires 1.

What is claimed is:
 1. An aiming device for insertion of aKirschner-wire to treat a target bone, comprising: an aiming blockpermitting placement of a Kirschner-wire against the target bone; and aforceps connected to the aiming block, the forceps being configured toclamp to the target bone, wherein the aiming block can be put againstthe target bone while the forceps is clamped to the bone.
 2. The aimingdevice according to claim 1, wherein the forceps comprise a ratchetmechanism fixing legs thereof in a desired clamping position on thebone.
 3. The aiming device according to claim 1, wherein the forcepscomprise a plurality of levers enabling single handed use thereof. 4.The aiming device according to claim 1, wherein an orientation of theaiming block relative to the bone is adjustable in a first plane.
 5. Theaiming device according to claim 1, further comprising a guide memberattached to the aiming block, the guide member being moveable relativeto the aiming block in a second plane.
 6. The aiming device according toclaim 5, wherein the guide member is configured to receive aKirschner-wire and is pivotable within the aiming block about an axis ofrotation.
 7. The aiming device according to claim 6, wherein the axis ofrotation passes through a longitudinal axis of the guide member.
 8. Theaiming device according to claim 5, further comprising a frictionalengagement mechanism between the guide member and the aiming blockself-locking the guide member at a predefined angle relative to theaiming block.
 9. An aiming device for insertion of a Kirschner-wire totreat a target bone, comprising: a) an aiming block permitting placementof a Kirschner-wire against the target bone; b) a guide member pivotallycoupled to the aiming block, the guide member configured to receive theKirschner-wire; and c) a fixing device coupled to the aiming block, thefixing device configured to clamp to the target bone to maintain theaiming block in a desired position relative to the target bone, whereinthe aiming block can be put against the target bone while the fixingdevice is clamped to the bone, wherein the fixing device comprises aforceps.
 10. An aiming device for insertion of a Kirschner-wire to treata target bone, comprising: a) an aiming block permitting placement of aKirschner-wire against the target bone; b) a guide member pivotallycoupled to the aiming block, the guide member configured to receive theKirschner-wire; and c) a fixing device coupled to the aiming block, thefixing device configured to clamp to the target bone to maintain theaiming block in a desired position relative to the target bone, whereinthe aiming block can be put against the target bone while the fixingdevice is clamped to the bone, wherein at least one of the aiming blockand the guide member is made of a radiolucent material.
 11. The aimingdevice according to claim 10, wherein the at least one of the aimingblock and the guide member made of a radiolucent material is formed ofPEEK.